This present invention relates, in general, to electronics, and more particularly, to semiconductor device structure and methods of forming the device structure. Diodes are a common type of semiconductor component that are used in both discrete and integrated forms. Semiconductor diodes conduct current when a positive voltage is applied from an anode to a cathode of the device. Conversely, diodes are non-conductive when a negative voltage is applied from the anode to the cathode. A common application for a diode is to rectify a signal. In particular, a diode is often used in the secondary side of switching power supplies. In this application, the diode is in the main power supply path coupled for delivering power to a load. Thus, the rectifying diode can conduct substantial currents when coupled to the load and storage device under regulation. The rectifying diode has a second function. The diode prevents current conduction from the load when the secondary winding of the transformer reverses polarity. The difference between the load voltage and secondary winding voltage can be substantial depending on the application.
The rectifying diode affects power supply efficiency. The principal loss is associated with the forward voltage drop of the rectifier diode during the conducting portion of a switching power supply operating cycle. The trade-off for increasing the size of the rectifying diode to reduce the forward voltage drop is to raise switching and leakage losses. Utilizing a Schottky diode as the rectifying diode lowers the forward voltage drop thereby improving operating efficiency. It is also important that the leakage current under reverse bias conditions be maintained or reduced when compared to other competing technologies. A high leakage current degrades operating efficiency thereby reducing the advantage of the low forward voltage drop of the Schottky diode.
Accordingly, it would be advantageous to have a diode having reduced leakage current under reverse bias conditions and a low forward voltage drop under forward bias conditions. The advantages could be used to optimize device operating efficiency, form factor, or both. It would be of further advantage if the method of manufacture of the device reduces complexity, time, and cost to produce the diode.